A plurality of white-light LEDs are often used for LED modules of the type mentioned. A white light LED module can be defined as generating light that is composed of different colors that are especially selected so that, when they are blended together, the result is percieved as white light. These LEDs generally contain an LED chip, which emits short-wave, for example violet, blue or blue-green, light, and a conversion element, for example a luminescent material. The conversion element converts part of the light emitted by the LED chip into light having a longer wavelength, thus giving rise to the impression of white light. Perhaps the most efficient and commonly used white-light LED has blue-emitting GaN-based LED chips and a conversion element which emits in the yellow-orange spectral region are usually used.
Due to the above-described type of light generation, LED modules constructed with these white-light LEDs have a spectrum with a strong blue and yellow-orange component. As regards other colors, the spectrum has distinct gaps, particularly in comparison with other conventional white-light sources, such as incandescent lamps. This can impair the color impression made by the LED module. Furthermore, many applications provide for conventional white-light sources, such as incandescent lamps, to be replaced by LED modules, in which case the radiation spectrum is intended to be as similar as possible or the exchange is intended to be inconspicuous to the observer. Also, a white color impression that is as true to life as possible is often desirable for aesthetic reasons.